The art of the present invention relates to sheet metal housings in general and more particularly to blower fan housing assemblies used in heating ventilating and air conditioning (HVAC) systems. The present art apparatus and method of manufacture continuously forms a rolled, lanced, and/or slit seam which locks the housing sides or panels with a perimeter wrapper sheet. The manufacturing apparatus and method of manufacture uniquely rotates two housing sides or panels and a preformed perimeter wrapper through one or more rollers which form a lanced and/or slit seam at the perimeter interface of the panels and wrapper.
Housings of various sizes and configurations are often employed in forced air furnaces and/or air conditioners and typically have a blower mounted therewith. The blower provides the ventilating air flow for heating, ventilating, and air conditioning systems. That is, the ventilating air flow forced through or over a heat exchanger or evaporator provides the desired air heating or cooling. A conventional blower housing is generally manufactured from sheet metal often having a painted, galvanized, or aluminized coating. The housing typically supports the blower (in the form of a powered blower wheel) and comprises two blower sides or panels with a wrapper sheet formed and attached around a perimeter interface. The blower wheel creates the required high volume of air flow. The wrapper sheet is substantially positioned between and formed or wrapped around a substantially parabolic radius contour of the two blower housing panels with a seam or joint peripherally created there between. The seam or joint must secure or lock the panels and wrapper whereby lateral or radial movement there between is prohibited during powered blower operation. The seam or joint must also prohibit any air flow leakage from the housing perimeter or peripheral interface.
Prior art seaming or joining of the wrapper to the housing panels varies from manufacturer to manufacturer and includes welding, flanging, or stacking of the panels and wrapper. Many manufacturers form a flange on either the wrapper or the panels and spot weld the combination of panels and wrapper around the perimeter interface. This prior art method of attachment is time consuming, labor intensive, and often represents a health and safety risk to the assembler. It is also prohibits coating of the sheet metal with a non-conductive coating prior to assembly. Other manufacturers utilize one or more discrete stakes, punches, or crimps around the seam. These prior art methods eliminate some of the safety and environmental issues associated with welding but are also time consuming and labor intensive, and often produce a seam which is inferior to the aforementioned welded seam.
The prior art housing assembly techniques and equipment are also dedicated or designed to produce only one type, style, diameter, or width of blower housing and utilize a specific thickness of sheet metal. HVAC equipment utilizes many different types, styles, diameters, and widths of blower housings in order to satisfy the air flow requirements of the system and the environment served. Different sizes of blower housings also utilize different thicknesses of sheet metal. Many of the prior art housing assembly techniques and equipment are also dedicated or designed for a specific sheet metal thickness.
The present art utilizes a continuous roll and lance (or slit) lock method which produces a superior rolled seam in less time than the prior art welding, punching, staking, or crimping systems. The present art assembly apparatus also allows a manufacturer to produce a wide variety of housing types, styles, diameters, or widths with a minimal setup or changeover adjustment. The present art also accommodates a plurality of sheet metal thicknesses and material types. Although rollforming of seams between flat sheet metal materials is recognized within various industries, simultaneous rollforming and lancing of housings or blower housings has not heretofore been performed. That is, it is difficult to create a uniform rolled and lanced seam on the parabolic peripheral geometry of the housing.
The present art blower housing and method of manufacture incorporates a continuous lance and/or slit rolled seam at the housing peripheral interface which closes and interlocks the edge flanges of the wrapper and panels together. For the preferred embodiment, the preformed housing side panels are inserted into preformed wrapper edge flanges and the resultant edge flange/panel sandwich is fed through one or more specially formed rollers which peripherally lance/slit, and roll the edge seams (i.e. a sandwich) with a single and continuous operation. That is, both sides are locked and seamed simultaneously as the lance and slit rollers follow around the outer perimeter or periphery of the housing. This configuration simultaneously locks the panels and wrapper together to form a seam without a lateral or radial movement between the wrapper and panels. The locking and seaming technique allows the housing to withstand blower loads and vibrations without failure and prohibits any gap between the panels and wrapper through which air leakage could occur.
The present art method of manufacture allows the blower housing to be constructed from different types and thickness of sheet materials and further allows the sheet materials to be coated, i.e. painted, galvanized, aluminized, or of dissimilar metals prior to assembly. No primary indexing cycles or secondary welding, punching, staking, or flanging operations are required. The rollers and holding fixture or chuck height and width is fully adjustable for any type of housing style, diameter, width, or material thickness.
Accordingly, it is an object of the present invention to provide a lance/slit seamed housing and method of manufacture which provides a secure rolled and lanced/slit seam between the housing side panels and the peripheral wrapper in a quick, easy, and safe manner.
Another object of the present invention is to provide a lance/slit seamed housing and method of manufacture which provides a continuously rolled seam without gaps and does not require primary indexing or secondary punching, crimping, or staking operations.
A further object of the present invention is to provide a lance/slit seamed housing and method of manufacture which may utilize pre painted or coated materials having a plurality of thicknesses and compositions.
A still further object of the present invention is to provide a lance/slit seamed housing and method of manufacture which is quickly and easily capable of formation into a plurality of blower housing styles, types, diameters, or widths.
A yet further object of the present invention is to provide a blower housing and method of manufacture which is easy and economical to manufacture in a variety of sizes with the same assembly machines.
A yet further object of the present invention is to provide a blower housing and method of manufacture having locking lances or slits and which provides a substantially smooth seam.